SEATTLE (AP) — Boeing is offering a voluntary layoff plan to prepare for an aircraft industry that the CEO says will take time to recover from the coronavirus pandemic.

CEO David Calhoun didn’t rule out involuntary job cuts later. Boeing's airline customers are seeing a massive decline in revenue because of travel restrictions to contain the spread of the virus, and many have made their own early-out offers to employees.

Boeing was weakened before the virus hit as it grappled with the grounding of its 737 Max airliner after two deadly crashes.

In a letter to employees, Calhoun said Boeing needs to start adjusting to the likelihood that the size of Boeing’s market will be different after the virus. Under the voluntary layoff plan, eligible employees will be able to leave with a severance package of pay and benefits. Calhoun said more information will be provided in three to four weeks.